So I looked at Phil's list and said "Holy Moly" then realized that for extended trips I carry pretty much the same. I've never found the need for a backup generator and I carried a spare tire for a while and finally dumped that. Stuff like spare water pumps and toilet valves etc. can be left behind if you have a toad to go fetch parts.
I got Benchmark maps for my trip out west and never got to the states I bought them for. A waste of $125 for sure. They are pretty though and made for some great arm chair dreaming in the off season.